Synthesis And Electrocatalytic Properties Of Pt Nanoparticles Supported On Functionalized Graphene

As a kind of novel green energy device, Direct Methanol Fuel Cell(DMFC) has attracted much attention due to their low-pollution, system simplicity and high energy conversion effieieney. Now, to prepare catalyst materials with the high stability and activity is the hotspot research of DMFC. However, the supporting materials are the key to the performance of catalysts; Graphene with good physical and chemical properties has a potential application prospect in catalysis. In this paper, functional graphene supported Pt anode catalysts were prepared and their electrochemical properties and stability were studied in detail.The main results obtained are as follows:1. A series of nitrogen-doped reduced graphene oxide nanocomposites(N-RGO)derived by pyrolysis of graphene oxide(GO)/polyani(ANI) composites with varied mass ratio of GO and aniline were used as support for immobilization of Pt nanoparticles. Transmission electron microscopy(TEM), X-ray powder diffraction(XRD), Raman spectroscopy and X-ray photoelectron spectroscopy(XPS) were used to characterize the morphology and microstructure of the prepared catalysts. The electrocatalytic activities of the as-prepared catalysts for CO stripping and methanol oxidation were investigated by cyclic voltammetry and chronoamperometry. The catalyst made with GO/ANI ratio of about 1:1.3 had better CO tolerance than other samples, and its specific mass activity was 160.8 A·g-1, which also exhibited higher methanol catalytic activity, better tolerance to CO poisoning and better electrochemical stability than those on RGO without N doping.2. Pt/ANI-RGO and Pt/PANI-RGO catalysts were prepared using the ANI and PANI noncovalently functionalized reduced graphene oxide(RGO) as supported materials. The results showed that the functionalized RGO helps to decrease the distribution range and size of Pt nanoparticles. Electrochemical studies revealed thatthe Pt/ANI-RGO and Pt/PANI-RGO nanocomposites with the higher electrochemical active surface area, its specific mass activity was 125.6 A·g-1and 86.4 A·g-1respectively, much higher than 77.3 A·g-1 of Pt/RGO, which showed excellent electrocatalytic activity toward methanol oxidation. But the introduction of ANI and PANI into Pt/RGO catalyst does not show an obvious contribution to the methanol oxidation.3. Pt/PVP-RGO catalyst was prepared using the PVP noncovalently functionalized RGO as supported materials. The result showed that the functionalized RGO decreased the distribution range and size of Pt nanoparticles. The results of electrochemical testing indicated that the introduetion of PVP into Pt/RGO catalyst had not a positive impact on enhaning the activity for methanol oxidation. But Pt/PVP-RGO catalyst showed excellent electrocatalytic stability toward methanol oxidation reaction.4. Pt/MV-RGO catalyst was prepared using the MV noncovalently functionalized RGO as supported materials. The results showed that the MV-RGO improved the distribution of Pt nanoparticles. Furthermore, the electrochemical active surface area of Pt/MV-RGO catalysts was 24.7 m2·g-1(almost 3 times higher than Pt/RGO), which showed excellent electrocatalytic activity toward methanol oxidation and oxygen reduction reaction. The peak current of methanol oxidation over the Pt/MV-RGO electrode was 221.4 A·g-1, which was 2.6 times as high as that over the Pt/RGO electrode. And Pt/MV-RGO also showed the better electrochemical stability than those of the Pt/RGO toward methanol oxidation reaction.